This invention concerns a drive arrangement within a small electric instrument, especially a battery-operated electronic clock of the type which includes a motor comprising a coil, at least two stator laminations and a rotor, the motor being arranged in a casing together with a circuit board which contains an electronic circuitry.
All components of presently known small electric instruments, especially clocks with a stepping motor drive, are designed in the form of individual parts and are mounted within bearings suitable for such parts. This holds true not only for parts of a clockwork but also for circuit boards, the stepping motor, battery contact elements and the like. The independent suspension or mounting of these components, however, requires a substantial number of separate steps to accomplish their individual assembly, and it becomes usually necessary to provide several fastening elements in order to hold these parts in their mounted position.
In view of these circumstances it is the object of the invention to provide a drive arrangement within a small electric instrument, especially a battery-operated clock, which is simple in construction and initial assembly.
It is another object of the invention to provide such a drive arrangement which can be inserted in the casing of the instrument without the need of additional adjustments and which can be removed from the casing in the same manner. The invention solves this problem in which static components of a drive mechanism, e.g., the coil, stator laminations and circuit board are assembled together, before installation as a unit within the housing of the instrument. The housing includes locating elements against which the circuit board is applied to retain the board in a preselected position within the housing.
The placement of at least the static parts of the motor on the circuit board results in a module that can be assembled prior to its installation and which can be inserted into, and removed from, the casing of the instrument by practically one single manipulation. However, it is also possible, depending on the type of the specific instrument, to pre-assemble on the circuit board, without any difficulties, other components of the instrument in addition to the static parts of the motor, thus reducing in all instances the number of separate components which require separate installation, or insertion and fastening within the casing.